Pathway-specific targeting of GAB(A) a receptor subtypes to somatic and dendritic synapses in the central amygdala

Delaney, A. J. and Sah, P. (2001) Pathway-specific targeting of GAB(A) a receptor subtypes to somatic and dendritic synapses in the central amygdala. Journal of Neurophysiology, 86 2: 717-723.

Author Delaney, A. J.
Sah, P.
Title Pathway-specific targeting of GAB(A) a receptor subtypes to somatic and dendritic synapses in the central amygdala
Journal name Journal of Neurophysiology   Check publisher's open access policy
ISSN 0022-3077
Publication date 2001-01-01
Sub-type Article (original research)
Volume 86
Issue 2
Start page 717
End page 723
Total pages 7
Place of publication Bethesda
Publisher American Physiological Society
Language eng
Abstract Neurons in the central amygdala express two distinct types of ionotropic GABA receptor. One is the classical GABA(A) receptor that is blocked by low concentrations of bicuculline and positively modulated by benzodiazepines. The other is a novel type of ionotropic GABA receptor that is less sensitive to bicuculline but blocked by the GABA(C) receptor antagonist (1,2,5,6-tetrohydropyridine-4-yl) methylphosphinic acid (TPMPA) and by benzodiazepines. In this study, we examine the distribution of these two receptor types. Recordings of GABAergic miniature inhibitory postsynaptic currents (mIPSCs) showed a wide variation in amplitude. Most events had amplitudes of <50 pA, but a small minority had amplitudes > 100 pA. Large-amplitude events also had rise times faster than small-amplitude events. Large-amplitude events were fully blocked by 10 muM bicuculline but unaffected by TPMPA. Small amplitude events were partially blocked by both bicuculline and TPMPA. Focal application of hypertonic sucrose to the soma evoked large-amplitude mIPSCs, whereas focal dendritic application of sucrose evoked small-amplitude mIPSCs. Thus inhibitory synapses on the dendrites of neurons in the central amygdala express both types of GABA receptor, but somatic synapses expressed purely GABA(A) receptors. Minimal stimulation revealed that inhibitory inputs arising from the laterally located intercalated cells innervate dendritic synapses, whereas inhibitory inputs of medial origin innervated somatic inhibitory synapses. These results show that different types of ionotropic GABA receptors are targeted to spatially and functionally distinct synapses. Thus benzodiazepines will have different modulatory effects on different inhibitory pathways in the central amygdala.
Keyword Neurosciences
Physiology
Extrasynaptic Gaba(a) Receptors
Gabaergic Neurons
Pyramidal Cells
Rat Hippocampus
Alpha Subunits
In-vitro
Brain
Pharmacology
Complex
Benzodiazepines
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collection: Queensland Brain Institute Publications
 
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Created: Mon, 13 Aug 2007, 22:28:22 EST